CN112034689B

CN112034689B - Immersion liquid temperature control device of immersion lithography machine

Info

Publication number: CN112034689B
Application number: CN202010994847.1A
Authority: CN
Inventors: 李小平; 曹迪
Original assignee: Wuhan Intelligent Equipment Industrial Institute Co ltd; Huazhong University of Science and Technology
Current assignee: Wuhan Micro Environmental Control Technology Co ltd
Priority date: 2020-09-21
Filing date: 2020-09-21
Publication date: 2021-10-08
Anticipated expiration: 2040-09-21
Also published as: CN112034689A

Abstract

The invention provides an immersion liquid temperature control device of an immersion lithography machine, which comprises: the first-stage temperature control module adjusts the temperature of the PCW in the PCW circulation loop by controlling the heating power and the flow of the PCW circulation loop and adjusts the temperature of the UPW recovered from the photoetching machine by exchanging heat between the PCW circulation loop and the UPW circulation loop so as to enable the temperature of the UPW to reach a stable set value; the second-stage temperature control module divides the UPW liquid of which the temperature is adjusted by the first-stage temperature control module into two UPW paths, and adjusts the temperatures of the two UPW paths based on the difference of the heat loads of the two UPW paths so that the temperature of the two UPW paths is kept at a set value; and injecting two paths of UPW (unified power flow) flowing out of the second-stage temperature control module into the immersion lithography machine, so that the immersion lithography machine can work based on a UPW immersion flow field. The invention controls the heat exchange between the PCW temperature and flow and the immersion liquid, and has buffer capacity for PCW temperature fluctuation.

Description

Immersion liquid temperature control device of immersion lithography machine

Technical Field

The invention belongs to the technical field of immersion lithography, and particularly relates to an immersion liquid temperature control device of an immersion lithography machine.

Background

Two final technical indexes affecting the process node of the immersion lithography machine are resolution and overlay accuracy. Since the immersion lithography machine is immersed with immersion liquid between the last projection objective and the silicon wafer, the resolution is related to the wavelength of the laser source, the process influence factor and the numerical aperture according to the Rayleigh formula.

Wherein k is₁Representing a process impact factor; r represents the resolution of the photoetching machine; λ represents the wavelength of the laser light source; NA represents the numerical aperture of the lithography machine; n represents the immersion medium refractive index; θ represents an incident angle of the light source; since the refractive index of the medium changes due to temperature fluctuation, maintaining temperature stability is critical to ensure the resolution index.

In terms of overlay accuracy, where the immersion liquid is considered to be part of the last lens of the projection optics, the optical quality of the liquid film will greatly affect the imaging outcome. The temperature fluctuation of the fluid causes the refractive index change, the liquid film evaporation in the scanning process can bring the thermal deformation of the silicon chip and possibly bring the aberration change, so one of the important factors influencing the optical quality of the liquid film is the temperature of the immersion flow field.

According to the principle that the resolution and the alignment precision of the process node of the photoetching machine are affected, the temperature stability, the adjusting range and the adjusting speed of the ultrapure water injected into the immersion unit are important to the factors. In addition, the immersion liquid temperature control system is attached to the immersion liquid water treatment module, and based on the internal process structure of the photoetching machine, the immersion liquid transmission pipeline is long, the experienced heat load is complex, and the immersion liquid temperature control system needs to adapt to relatively severe plant input conditions, which bring difficulty to the temperature control of the immersion liquid. The photoetching machine is used as high-efficiency and high-cost semiconductor important equipment, and the equipment is required to be ensured to have long-term operation reliability. Therefore, the research of the immersion liquid temperature control system which has high control precision and long-term operation and is excellent in robustness under various conventional disturbances is an important research of the immersion lithography.

Chinese patent 201020596742.2 describes an immersion liquid temperature control device for an immersion lithography machine, which can ensure the temperature stability requirement of an immersion liquid flow field by using a thermoelectric refrigeration mechanism and measure the immersion liquid temperature characteristic in real time. In an actual photoetching machine, the immersion photoetching machine has extremely high requirements on immersion liquid, deionized and degasified ultrapure water is generally adopted, and the immersion liquid temperature control is not beneficial to the pollution control of the immersion liquid by adopting a thermoelectric refrigeration mechanism. Chinese patent 201020596742.2 utilizes the heat exchange principle, and adopts a PFA heat exchanger and a flow servo valve to perform precise temperature control on the immersion liquid, thereby reducing the pollution to the immersion liquid; moreover, 201020596742.2 provides temperature control of the immersion fluid primarily through the TCU, and lacks secondary temperature control capability and flexibility in controlling temperature of the end immersion fluid.

Chinese patent 201310079232.6 describes an immersion liquid temperature control device for immersion lithography machine, which utilizes multi-stage heat exchange and immersion liquid return water to ensure the temperature stability of the immersion flow field and measure the immersion liquid temperature characteristic in real time. In an actual operating environment of the lithography machine, the temperature of an input end is possibly higher than a target temperature value, and the temperature of factory service Process Cooling Water (PCW) is lower than the temperature of controlled liquid UPW, so that the device can only meet the capacity of temperature reduction and temperature regulation, and has strict requirements on the temperature range of factory service end ultrapure Water (UPW).

US7433015B2 describes a liquid temperature control device integrated into an immersion lithography system for removing impurities, degassing, flow, pressure and temperature control of the incoming immersion liquid. The apparatus uses a process coolant (which may be, for example, PCW) to exchange heat with an immersion liquid (which may be, for example, UPW) via a heat exchanger to control the immersion liquid temperature. Because it does not set up the return circuit to the part of temperature control for its temperature control precision is not high, owing to only adopt the flow of adjusting the heat exchanger coolant liquid that lets in to control the temperature of immersion fluid, the coolant liquid temperature generally is less than the immersion fluid, so only can play the effect of cooling accuse temperature, can not satisfy the control objective that is higher than the input temperature value.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide an immersion liquid temperature control device of an immersion lithography machine, and aims to solve the problems that the temperature control of the conventional immersion lithography machine lacks buffer capacity on PCW temperature fluctuation and the temperature stability cannot meet the requirement.

In order to achieve the above object, the present invention provides an immersion liquid temperature control device of an immersion lithography machine, comprising: the temperature control system comprises a first-stage temperature control module and a second-stage temperature control module;

the first-stage temperature control module comprises a process cooling water PCW circulation loop and an ultrapure water UPW circulation loop, UPW recovered from the immersion lithography machine flows into the UPW circulation loop, and the first-stage temperature control module adjusts the temperature of UPW recovered from the lithography machine by adjusting the temperature of PCW in the PCW circulation loop and by carrying out heat exchange on the PCW circulation loop and the UPW circulation loop so that the temperature of UPW recovered from the immersion lithography machine reaches a stable set value; the first-stage temperature control module controls the temperature of the PCW by controlling the heating power and the flow of the PCW circulation loop;

the second-stage temperature control module is used for dividing the UPW liquid of which the temperature is adjusted by the first-stage temperature control module into two UPW paths, and adjusting the temperature of the two UPW paths based on the difference of the thermal loads of the two UPW paths so that the temperature of the two UPW paths is kept at the set value; the second-stage temperature control module controls the heating power and the flow of the two UPW paths so as to control the temperature of the two UPW paths to be stably kept at the set value; the thermal load of each UPW passage corresponds to the temperature disturbance quantity of each UPW passage; and injecting two paths of UPW (unified Power supply) flowing out of the second-stage temperature control module into the immersion lithography machine, wherein one path of UPW is used for filling a UPW immersion flow field of the immersion lithography machine, and the other path of UPW is used for sealing the UPW immersion flow field, so that the immersion lithography machine can work based on the UPW immersion flow field.

In an alternative embodiment, the UPW circulation loop circulates UPW fluid, the path of which includes: a second circulation pump and the heat exchanger;

the output end of the second circulating pump is connected with the third end of the heat exchanger, and the input end of the second circulating pump is connected with the fourth end of the heat exchanger; flowing UPW recovered from the immersion lithography machine into a third end of the heat exchanger;

the second circulating pump is used for stabilizing the flow of the UPW circulating loop and enabling part of UPW subjected to temperature control by the heat exchanger to flow back to the third end of the heat exchanger so as to improve the temperature stability of the UPW flowing back to the third end of the heat exchanger and the UPW mixed liquid at the third end of the heat exchanger; the heat exchanger is used for realizing heat exchange between the PCW circulation loop and the UPW circulation loop.

In an alternative embodiment, the PCW circulation circuit is configured to circulate PCW fluid, and the components of the path include: the system comprises a first circulating pump, a heat exchanger, a one-way valve, a first flow sensor and a first temperature sensor;

the first stage temperature control module further comprises: a first flow servo valve, a first heater, a second temperature sensor, a second flow sensor, a first controller and a third temperature sensor;

the input end of the first circulating pump is connected with the first end of the heat exchanger, and the output end of the first circulating pump is connected with the input end of the first flow servo valve; an output of the first flow servo valve outputs PCW; the PCW flowing into the plant input PCW end flows into the input end of the first heater, and the output end of the first heater is connected with the second end of the heat exchanger; the input end of the one-way valve is connected with the output end of the first circulating pump, and the other end of the one-way valve is connected with the output end of the heater and the second end of the heat exchanger;

the first temperature sensor is used for detecting the temperature of the PCW in the PCW circulation loop, and the second temperature sensor is used for detecting whether the temperature of the PCW flowing into the first heater is kept stable or not;

the first circulating pump is used for adjusting the flow of the PCW circulating loop; the first flow sensor is used for detecting the flow of a PCW circulation loop, and the second flow sensor is used for detecting the flow of the PCW circulation loop;

the first stage temperature control module further comprises: a third temperature sensor; the third temperature sensor is configured to detect a UPW temperature flowing out of the fourth end of the heat exchanger;

the first controller is configured to control the heating power of the first heater in conjunction with the detection results of the first temperature sensor and the third temperature sensor, and to control the first flow servo valve in conjunction with the detection results of the first flow sensor and the second flow sensor to control the flow rate of the PCW flowing into and out of the PCW circulation circuit; and the bidirectional temperature control of the temperature rise and the temperature fall of the PCW in the PCW circulation loop is realized by combining the dual control of the heating power and the PCW flow.

In an alternative embodiment, the components of the UPW circulation loop further comprise: a thermal buffer tank;

one end of the thermal buffer tank is connected with the fourth end of the heat exchanger, the other end of the thermal buffer tank is connected with the input end of the second circulating pump, and the other end of the thermal buffer tank is used as the output end of the UPW circulating loop;

the thermal buffer tank is used for fully mixing the UPW flowing in the UPW circulation loop and inhibiting the temperature fluctuation of the UPW.

In an alternative embodiment, the second stage temperature control module comprises: the first UPW passage, the second UPW passage, the third temperature sensor, the fourth temperature sensor, the third flow sensor, the fourth flow sensor and the second controller;

UPW output by the output end of the UPW circulation loop respectively flows into a first UPW passage and a second UPW passage;

the components of the first UPW path include: a second flow servo valve, a second heater, a third temperature sensor, and a third flow sensor;

the components of the second UPW path include: a third flow servo valve, a third heater, a fourth temperature sensor and a fourth flow sensor;

the third temperature sensor is used for detecting the temperature of the UPW in the first UPW passage, and the fourth temperature sensor is used for detecting the temperature of the UPW in the second UPW passage; the third flow sensor is used for detecting the flow of the UPW in the first UPW passage, and the fourth flow sensor is used for detecting the flow of the UPW in the second UPW passage;

the second controller is used for determining the heat load difference of the first UPW passage and the second UPW passage according to the detection results of the third temperature sensor and the fourth temperature sensor, and controlling the heating power of the third heater and the fourth heater based on the heat load difference and the detection values of the third flow sensor and the fourth flow sensor so that the temperature of the UPW in the first UPW passage and the second UPW passage can be stably maintained at the set value.

In an optional embodiment, the UPW circulation loop further comprises: a throttle valve;

one end of the throttle valve is connected with the output end of the second circulating pump, and the other end of the throttle valve is connected with the third end of the heat exchanger; the throttle valve is used to regulate the flow of the UPW circulation loop.

In an optional embodiment, the first stage temperature control module further comprises: a pressure reducing valve;

the pressure reducing valve is a constant value pressure reducing valve, the input end of the pressure reducing valve is connected with a plant service input PCW end, and the output end of the pressure reducing valve is connected with the input end of the first heater and used for keeping the pressure of the PCW entering the PCW circulation loop stable.

In an alternative embodiment, the UPW recovered from the immersion lithography machine is purified before flowing into the UPW circulation loop.

Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:

the invention provides a temperature control device of an immersion lithography machine, which combines a double loop of immersion liquid and cooling liquid with a heat exchanger, thereby not only ensuring the temperature control efficiency, but also realizing the stable control of the immersion liquid temperature; the invention carries out heating and refrigerating dual-function regulation on the cooling liquid loop, and ensures the temperature control capability under the conditions of different plant input conditions and temperature set values; the thermal buffer tank is used for inhibiting high-frequency temperature fluctuation; the two UPW injection solutions are respectively controlled by the heaters to realize the stable, accurate and stable control of immersion liquid in immersion lithography and improve the temperature control precision.

The invention provides a temperature control device of an immersion lithography machine, which controls the heat exchange between the temperature and the flow of a PCW and immersion liquid, constructs a constant flow circulation loop, reduces the flow fluctuation of the PCW in a heat exchanger, can effectively inhibit the influence of the input PCW temperature disturbance on the heat exchange, improves the stability of the heat exchange in primary control, and realizes the temperature control in two directions and a larger range by respectively controlling the flow and the temperature of the PCW by introducing a servo valve and a heater so as to adapt to different UPW, PCW input temperature and target temperature values and improve the adaptability of products to different plant conditions. And the difference of the two paths of heat loads is compensated by the heaters respectively at the last two branch pipelines, so that the finally output two paths of injection liquid can synchronously reach the temperature set value.

Drawings

FIG. 1 is a schematic structural diagram of an immersion liquid temperature control apparatus according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an immersion liquid circulation process and immersion unit and liquid injection port provided in an embodiment of the present invention;

the same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein: 100 is a first-stage temperature control module, 200 is a second-stage temperature control module, 1 is a UPW input terminal, 2 is a coolant PCW input terminal, 3 is a first-stage controller, 4 is a second-stage controller, 5 is a heat exchanger, 6 is a first flow servo valve, 7 is a first heater, 8 is a first circulation pump, 9 is a thermal buffer tank, 10 is a second heater, 11 is a third heater, 12 is a fifth temperature sensor, 13 is a first temperature sensor, 14 is a third temperature sensor, 15 is a fourth temperature sensor, 16 is a first throttle valve, 17 is a second circulation pump, 18 is a second flow servo valve, 19 is a third flow servo valve, 20 is a second throttle valve, 21 is a second output terminal of the UPW, 22 is an on-off valve, 23 is a first check valve, 24 is a first filter, 25 is a pressure sensor, 26 is a sixth temperature sensor, 27 is a second filter, 28 is a pressure reducing valve, and, 29 is a second flow sensor, 30 is a second temperature sensor, 31 is a PCW output terminal, 32 is a second check valve, 33 is a first flow sensor, 34 is a third flow sensor, 35 is a fourth flow sensor, 36 is a third output terminal of UPW, 37 is a fourth output terminal of UPW, 38 is an immersion temperature control device, 39 is a UPW recovery device, 40 is a UPW pretreatment device, 41 is a projection objective, 42 is an immersion unit, 43 is a silicon wafer, 44 is a workpiece table, 45 is an immersion flow field, 46 is a PCW circulation loop, and 47 is a UPW circulation loop.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The technical problems to be solved by the invention are as follows: in order to achieve the preset alignment precision of the immersion lithography, high-precision temperature control needs to be carried out on immersion liquid in an immersion lithography machine; the UPW inlet temperature provided by the plant service end of the immersion lithography machine is different from the final set value, and in order to adapt to more plant conditions, the equipment is required to have the capacity of bidirectional temperature control and stability guarantee. The PCW temperature fluctuation of the coolant for UPW heat exchange provided by the plant service end of the immersion lithography machine is large, and in order to adapt to severe plant service conditions, the equipment needs to have the buffering capacity for the PCW fluctuation. When the process structure based on the immersion unit normally works, the two UPW injection liquid flows and the heat load are different, and the two output temperatures need to be ensured to be stabilized at set values.

Correspondingly, the invention discloses an immersion liquid temperature control system suitable for immersion lithography under various plant input conditions and temperature set values, which outputs multiple paths of immersion liquid with stable temperature and is used for forming a flow field of an immersion lithography machine to serve as a medium between an objective lens and a silicon wafer during exposure. The system comprises: the immersion liquid pipeline is used for immersion liquid flowing, immersion liquid to be temperature controlled enters the immersion liquid pipeline through a pipeline inlet, and the immersion liquid with stable temperature is output in two paths through an outlet of the immersion liquid pipeline after temperature control treatment; a process coolant loop for cooling or heating the immersion liquid, in which loop a process coolant is circulated; the temperature of the process coolant can be regulated by a flow servo valve and a heater that are input to the process coolant loop. And heat exchange between the process coolant and the immersion liquid is respectively and sequentially completed by using a heat exchanger. The addition of a buffer tank after the heat exchanger suppresses temperature fluctuations and employs an immersion liquid circuit in conjunction with the heat exchanger to obtain an immersion liquid with a stable temperature. And the heaters are respectively controlled for two paths of liquid injection required by the immersion lithography. The device system of the invention combines the immersion liquid and cooling liquid double loops with the heat exchanger to realize the temperature stability control of the immersion liquid, and carries out heating and refrigerating double-function regulation on the cooling liquid loop to ensure the temperature control capability under the conditions of different plant input conditions and temperature set values, the buffer tank is used for inhibiting high-frequency temperature fluctuation, and the two paths of injection liquid are respectively controlled by the heaters to realize the stable, accurate and stable control of the immersion liquid in immersion lithography, thereby improving the temperature control precision.

The invention provides an immersion liquid temperature control device of an immersion lithography machine. The device coarsely adjusts the UPW temperature to be close to a set value reference value by controlling the temperature and the flow of PCW circulation in the first stage, restrains the fluctuation of the UPW temperature through a thermal buffer tank in the later stage, compensates unstable thermal load caused by two-path UPW liquid injection flow adjustment by respectively adopting heater control before two-path liquid injection ports leading to an immersion head, and finally achieves the temperature stability required by an immersion flow field. Under the condition of a given input temperature range of the plant immersion liquid and the cooling liquid, the device can meet the requirement of arbitrarily selecting a set value at 20-24 ℃ under the working condition of a stable state, and the stability of less than or equal to 5mK/30s in a short time, less than or equal to 12mK/15min in a long time and +/-0.01 ℃ in a long time is achieved.

In one particular embodiment, the temperature control system comprises:

the temperature set value and the temperature stability of the multi-channel liquid injection are realized through two-stage temperature control. The first-stage temperature control is used for improving a temperature set value and roughly adjusting the temperature stability, and the second-stage temperature control is used for carrying out secondary adjustment according to the difference of loads of all paths and the difference of the set value.

In the first stage of temperature control, the temperature stability of the liquid after backflow is improved by adopting a UPW loop and a PCW loop, and heat exchange is carried out around the same heat exchanger.

Controlling the temperature of the PCW input to the heat exchanger by adjusting the heater power on the PCW circuit input line and the flow servo valve on the PCW circuit output line to adjust the temperature of the output UPW; the heater is arranged in an inlet pipeline of the PCW circuit, and the flow servo valve is arranged in an outlet pipeline of the PCW.

The thermal buffer tank is used to dampen temperature fluctuations, particularly high frequency fluctuations, and is located either inside the UPW loop or outside the UPW.

As a further preferred aspect of the present invention, a fixed displacement pump is introduced into the PCW circuit and placed in the line of the PCW output stage of the heat exchanger, thereby achieving stability of the flow rate of the PCW circuit and ensuring stability of heat exchange.

The thermal buffer tank is used to dampen temperature fluctuations, particularly high frequency fluctuations, and is placed in the interior of the UPW loop after the heat exchanger.

As a further preferred aspect of the present invention, a pressure reducing valve is added to the inlet PCW circuit to stabilize the pressure of the liquid entering the circuit, thereby stabilizing the operation of the pump and the servo valve.

As a further preferred aspect of the present invention, two temperature feedback points are provided in the first stage temperature control, the inner loop feedback point is provided at the inflow end of the PCW of the internal heat exchanger in the PCW loop, and the outer loop feedback point is provided at the first stage output line, so as to support the cascade control of the system to suppress the rapid disturbance in the inner loop.

As a further preferred aspect of the present invention, the multiple outputs ensure the stability of the output flow through the flow servo valve, and adjust the heater power of each output to compensate the difference between the thermal load of each output and the set value.

As a further preferred aspect of the present invention, the immersion liquid pipeline is provided with a plurality of temperature sensors, a part of the temperature sensors are used for monitoring the system state, a part of the temperature sensors are used for controlling the connection of the temperature controllers, and the temperature values detected by the temperature sensors are fed back to the corresponding temperature controllers, so that the temperature controllers are used for controlling the corresponding electro-hydraulic servo valves and heaters, and performing flow control and temperature control on the cooling liquid input into the process cooling liquid loop, thereby realizing precise immersion liquid temperature control.

As a further preferred aspect of the invention, the process coolant is water.

In a further preferred embodiment of the present invention, the immersion liquid is ultrapure water.

The temperature control system device provided by the invention is based on an immersion liquid pipeline (immersion liquid in the embodiment adopts ultrapure water, UPW) loop and a process cooling liquid loop (cooling liquid in the embodiment adopts water, PCW), utilizes the heat exchange principle of a heat exchanger, simultaneously adjusts the output temperature of a first-stage UPW by controlling the flow and temperature entering the PCW loop, and realizes the flow and temperature control of a second-stage two-way UPW immersion liquid by a direct heating mode.

Fig. 1 is a schematic view of an embodiment of an immersion liquid temperature control device according to an embodiment of the present invention. The temperature control device fluid cycle includes two stages of control modules 100, 200: the first stage control 100 is used for coarse temperature adjustment and the second stage control 200 is used for fine temperature adjustment. The controller 3 achieves 100 to 200 output temperature by adjusting 100 the flow into the PCW coolant loop and heater power, with the flow stabilized at a specified value of UPW. The controller 4 compensates the difference of thermal loads caused by different liquid injection flow rates of the two liquid injection branches by respectively controlling the heaters of the two liquid injection branches, and further improves the temperature control precision.

The UPW immersion first stage control 100 comprises a plant service port immersion UPW input 1, a coolant PCW input 2, an output 31, a heat exchanger 5, a heater 7, a flow servo valve 6, a thermal buffer tank 9, circulating pumps 8, 17, check valves 23, 32, a throttle valve 16, filters 24, 27, a switching valve 22, a pressure reducing valve 28, and a plurality of tapping points, which are access points of each sensor and are used for measuring the temperature (

sensors

12, 13, 26, 30), pressure (sensor 25) and flow (sensors 29, 33) of corresponding points, wherein the temperature sensors 12, 13 are precision temperature sensors, and the other temperature sensors are ordinary precision temperature sensors.

The UPW immersion liquid second stage control 200 includes immersion liquid UPW outputs 21, 36, 37, where 36, 37 inject the immersion flow field, heaters 10, 11, flow

servovalves

18, 19, throttle valve 20, filters 24, 27, on-off valve 22, pressure relief valve 28, a plurality of tap points that are access points for each sensor for measuring the temperature (sensors 14, 15) and flow (sensors 34, 35) of the corresponding point, where the temperature sensors 14, 15 are precision temperature sensors.

The first stage of control mainly comprises two loops, one is a UPW water pipeline (shown by a thin solid line in figure 2), UPW water to be temperature-controlled flows in from a water inlet 1 and passes through a heat exchanger 5 along a pipeline to exchange heat with PCW water so as to realize temperature control of the UPW water (immersion liquid), and finally the UPW water is circulated back to a position behind a UPW inlet filter 24 so as to improve the temperature and flow state of the UPW water before temperature control, and the loops have no flow loss. In the actual use process, the UPW water subjected to temperature control by the pipeline is conveyed to the second-stage temperature control module 200. The second is the PCW water circuit, which is a cooling water circuit. The primary means of temperature control is by regulating the flow and temperature into and out of the PCW water circuit. The device is provided with a heat exchanger 5 in a PCW water loop, and a controller 3 is used for respectively adjusting a hydraulic servo valve 6 and a heater 7 so as to realize heating and refrigerating bidirectional temperature control, and the specific process is as follows:

UPW water enters a UPW water pipeline of the temperature control system through a water inlet 1, and a switching valve 22, a one-way valve 23, a filter 24, a throttle valve 16, a heat exchanger 5, a booster pump 17 and a buffer tank 9 are sequentially arranged on the UPW water pipeline. The UPW water is determined by the switch valve 22 to have the on-off logic function, the one-way valve 23 prevents the UPW from flowing backwards, the filter 24 filters the UPW to ensure the cleaning requirement of the subsequent process and the heat exchange efficiency of the heat exchanger, the throttle valve 16 ensures the set flow to be stable, and the booster pump 17 provides the circulating power of the UPW loop 47 and simultaneously prevents the UPW water from flowing backwards. UPW water in the UPW pipeline exchanges heat through the heat exchanger 5, the UPW water after heat exchange is output to the buffer tank 9 through the UPW pipeline, one part of the outlet of the buffer tank flows back to the UPW inlet filter through the UPW loop 47, so that the temperature of the UPW water before temperature control is greatly improved before entering the heat exchanger for control, the whole temperature control efficiency is improved, and one part of the UPW water is output to the second-stage temperature control module 200 as immersion liquid. The UPW pipeline after the buffer tank 9 is replaced is also provided with a temperature sensor 12 which is connected with a controller 3 and is used for detecting the temperature of the UPW water after heat exchange. Pressure and

temperature sensors

25, 26 are provided at the UPW inlet for real-time monitoring whether the input pressure and temperature meet controllable input conditions.

The PCW water circuit includes a PCW input 2 output 31 to which cooling water (PCW water) is supplied that is recovered for cooling the UPW water. The inlet of the PCW water loop 46 is connected with a pressure reducing valve 28 in series to ensure that the inlet pressure is stable, the cleanliness of the PCW is ensured by a filter 27 to ensure the heat exchange efficiency of the heat exchanger 5, and the PCW loop 46 internally comprises the heat exchanger 5, a pump 8 and a one-way valve 32. The pump 8 ensures that the loop 46 is circulating at a steady flow rate, the check valve 32 prevents the loop flow direction from changing, and the PCW exchanges heat in the heat exchanger 5 with the UPW water in the UPW line passing through the heat exchanger, thereby completing the heat exchange. The heat-exchanged PCW water is recovered through the output terminal 31 to be recycled.

In addition, a heater 7 is arranged at the external inlet of the PCW water circuit, an electro-hydraulic servo valve 6 is arranged at the outlet of the PCW water circuit, and each electro-hydraulic servo valve and each heater are controlled by a corresponding controller 3 and are used for respectively controlling the flow and the temperature entering the PCW circuit, so that the temperature of the PCW water entering the heat exchanger of the PCW circuit is controlled, and corresponding temperature regulation is realized. A temperature sensor 13 is provided inside the PCW loop as one of the feedback points for feedback control, a flow sensor 33 for monitoring the stability of the loop flow. The loop inlet temperature sensor 30 is used to monitor the input PCW for compliance with plant output standards and the loop outlet flow sensor 29 is used to monitor the magnitude of the flow controlled by the electro-hydraulic servo valve.

In addition, a temperature controller is arranged on the UPW water pipeline behind the heat exchanger, namely a temperature sensor 12 is arranged behind the buffer tank 9 respectively, and the temperature sensors are used for detecting the temperature of the UPW water after heat exchange of the corresponding heat exchanger respectively. The temperature sensor is connected with the corresponding temperature controller 3, and feeds back the detected temperature value to the corresponding temperature controller 3, so that the corresponding actions of the electro-hydraulic servo valve 6 and the heater 7 can be controlled according to the temperature value to respectively control the flow and the temperature entering the PCW loop, the temperature of the PCW entering the heat exchanger 5 of the PCW loop is controlled, the accurate temperature control of the UPW water is realized, and the temperature fluctuation is inhibited through the buffer tank 9.

Specifically, water in the UPW pipeline firstly exchanges heat for the first time through the heat exchanger 5, and the temperature after heat exchange is fed back to the controller 3 through the temperature sensor 12, so that the controller 3 can automatically adjust the electrohydraulic servo valve 6 according to the temperature difference to adjust the flow rate entering and exiting the PCW loop, and the heater 7 adjusts the temperature entering the PCW loop 46, so that the temperature after heat exchange is close to a theoretical value, the UPW water after temperature control further reduces temperature fluctuation through the buffer tank 9, and is circulated by the pump 17 and mixed with UPW water before temperature control before entering the second-stage temperature control module 200 and after entering the buffer tank 9, so that the UPW water temperature and flow state before temperature control are improved.

The second level control comprises three UPW pipelines, wherein two of the three UPW pipelines are used for two-

way liquid injection

36 and 37 of an immersion unit of the immersion lithography machine, and the output of the immersion liquid is regulated by the

flow servo valves

18 and 19 and the heaters 10 and 11, so that the flow rate of the immersion liquid is stable and the temperature of the immersion liquid is stable. The bypass 21 is used for other functional interfaces, the bypass 21 has two functions, one branch flows to the ultrapure gas humidifying device and is used for humidifying the ultrapure gas, and the other branch is used for firstly flowing out of the equipment from the branch before various indexes such as the first-stage liquid injection temperature, the cleanliness and the like reach the standard, and is closed after the first-stage liquid injection reaches the standard, so that the liquid is switched to the 36 and 37 ways of liquid injection; where the first stage injection is UPW fluid in the first stage temperature control module and the throttle 20 is used to regulate bypass flow. The two liquid injection pipelines controlled by the flow and the temperature are provided with flow sensors 34 and 35 for monitoring the stability of the flow of the electro-

hydraulic servo valves

18 and 19, and temperature sensors 14 and 15 for detecting the output temperature are arranged behind the heaters and transmitting feedback signals to the controller to adjust the power of the heaters so that the output reaches a set temperature value.

Specifically, after water in the UPW pipeline passes through the first-stage temperature control module 100, the stability of output flow is ensured through the two

electrohydraulic servo valves

18 and 19, and the temperature of the outlet is fed back to the controller 4 through the temperature sensors 14 and 15, so that the controller 4 can automatically adjust the heaters 10 and 11 according to the temperature difference to adjust the finally output temperature, so that the temperature is close to a theoretical value, and the target temperature precision is achieved.

Fig. 2 shows a schematic diagram of an immersion liquid circulation process and an immersion unit and a liquid injection port according to an embodiment of the present invention, and fig. 2 shows the functions of a UPW recovery device 39, a UPW pretreatment device 40, and an immersion liquid temperature control device 38 in an immersion liquid control link of an immersion lithography machine. A silicon wafer 43 is placed on the stage 44, and an immersion flow field 45 formed by the UPW immersion liquid after temperature control by the immersion liquid temperature control device 38 is filled between the projection objective 41, the immersion unit 42, and the silicon wafer 43. The immersion flow field 45 absorbs heat generated in the projection lithography process, is recovered by the UPW recovery device 39, is purified by the UPW pretreatment device 40, and is output to the immersion liquid temperature control device 38, and the immersion liquid with stable UPW flow temperature is provided to the immersion unit 42 after being controlled by the immersion liquid temperature control device 38.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. An immersion liquid temperature control device of an immersion lithography machine, comprising: the temperature control system comprises a first-stage temperature control module and a second-stage temperature control module;

the first-stage temperature control module comprises a process cooling water PCW circulation loop and an ultrapure water UPW circulation loop, UPW recovered from the immersion lithography machine flows into the UPW circulation loop, and the first-stage temperature control module enables the temperature of the UPW recovered from the immersion lithography machine to reach a stable set value by adjusting the temperature of the PCW in the PCW circulation loop and adjusting the temperature of the UPW recovered from the lithography machine by carrying out heat exchange on the PCW circulation loop and the UPW circulation loop; the first-stage temperature control module controls the temperature of the PCW by controlling the heating power and the flow of the PCW circulation loop;

the UPW circulation loop circulates UPW liquid, and the parts of the circulation loop comprise: a second circulation pump and a heat exchanger; the output end of the second circulating pump is connected with the third end of the heat exchanger, and the input end of the second circulating pump is connected with the fourth end of the heat exchanger; flowing UPW recovered from the immersion lithography machine into a third end of the heat exchanger; the second circulating pump is used for stabilizing the flow of the UPW circulating loop and enabling part of UPW subjected to temperature control by the heat exchanger to flow back to the third end of the heat exchanger so as to improve the temperature stability of the UPW flowing back to the third end of the heat exchanger and the UPW mixed liquid at the third end of the heat exchanger; the heat exchanger is used for realizing heat exchange between the PCW circulation loop and the UPW circulation loop;

the PCW circulation circuit is used for circulating PCW liquid, and the components of the passage comprise: the system comprises a first circulating pump, a heat exchanger, a one-way valve, a first flow sensor and a first temperature sensor; the first stage temperature control module further comprises: a first flow servo valve, a first heater, a second temperature sensor, a second flow sensor, a first controller and a third temperature sensor; the input end of the first circulating pump is connected with the first end of the heat exchanger, and the output end of the first circulating pump is connected with the input end of the first flow servo valve; an output of the first flow servo valve outputs PCW; the PCW flowing into the plant input PCW end flows into the input end of the first heater, and the output end of the first heater is connected with the second end of the heat exchanger; the input end of the one-way valve is connected with the output end of the first circulating pump, and the other end of the one-way valve is connected with the output end of the heater and the second end of the heat exchanger; the first temperature sensor is used for detecting the temperature of the PCW in the PCW circulation loop, and the second temperature sensor is used for detecting whether the temperature of the PCW flowing into the first heater is kept stable or not; the first circulating pump is used for adjusting the flow of the PCW circulating loop; the first flow sensor is used for detecting the flow of a PCW circulation loop, and the second flow sensor is used for detecting the flow of the PCW circulation loop; the first stage temperature control module further comprises: a third temperature sensor; the third temperature sensor is configured to detect a UPW temperature flowing out of the fourth end of the heat exchanger; the first controller is configured to control the heating power of the first heater in conjunction with the detection results of the first temperature sensor and the third temperature sensor, and to control the first flow servo valve in conjunction with the detection results of the first flow sensor and the second flow sensor to control the flow rate of the PCW flowing into and out of the PCW circulation circuit; the bidirectional temperature control of the temperature rise and the temperature drop of the PCW in the PCW circulation loop is realized by combining the dual control of the heating power and the PCW flow;

the components of the UPW circulation loop further include: a thermal buffer tank; one end of the thermal buffer tank is connected with the fourth end of the heat exchanger, the other end of the thermal buffer tank is connected with the input end of the second circulating pump, and the other end of the thermal buffer tank is used as the output end of the UPW circulating loop; the thermal buffer tank is used for fully mixing UPW flowing in the UPW circulation loop and inhibiting UPW temperature fluctuation;

2. The immersion lithography apparatus of claim 1, wherein the second stage temperature control module comprises: the first UPW passage, the second UPW passage, the third temperature sensor, the fourth temperature sensor, the third flow sensor, the fourth flow sensor and the second controller;

3. The immersion lithography apparatus as claimed in claim 1, wherein said UPW circulation loop further comprises: a throttle valve;

4. The immersion lithography apparatus of claim 1, wherein said first stage temperature control module further comprises: a pressure reducing valve;

5. An immersion lithography machine immersion liquid temperature control apparatus according to any one of claims 1 to 3, wherein the UPW recovered from the immersion lithography machine is subjected to a purification process before flowing into the UPW circulation loop.